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USB superspeed peripherals

HuEl_264296
Level 5
25 sign-ins First solution authored 100 replies posted
Level 5

Hi,

I am using a CX3 to bridge a MIPI camera to USB.

The CX3 is booting from SPI FLASH.  There is no external I2C device connected.

In that case, do I still need the I2C pull-up resistors connected, or should it work without them?

 

The reason I ask is that my system works fine when I have the I2C resistors soldered in place (I see a live stream from the camera), but if I remove them, then the CX3 enumerates and appears in Device Manager, but I no longer see any images from the camera.

 

Thanks

Hugo

 

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1 Solution
JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello Hugo,

It is necessary to have pull up resistors on I2C lines of CX3. This is because the MIPI CSI-2 block of CX3 is configured over I2C interface as mentioned in section 1.4 of CX3 TRM. The CX3 TRM comes along with FX3 SDK and can be found in the following location:
C:\Program Files (x86)\Cypress\EZ-USB FX3 SDK\1.3\doc\firmware

Best Regards,
Jayakrishna

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3 Replies
JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello Hugo,

It is necessary to have pull up resistors on I2C lines of CX3. This is because the MIPI CSI-2 block of CX3 is configured over I2C interface as mentioned in section 1.4 of CX3 TRM. The CX3 TRM comes along with FX3 SDK and can be found in the following location:
C:\Program Files (x86)\Cypress\EZ-USB FX3 SDK\1.3\doc\firmware

Best Regards,
Jayakrishna
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HuEl_264296
Level 5
25 sign-ins First solution authored 100 replies posted
Level 5

Hi, thanks for that.

Yes, I eventually discovered that in the TRM.

I do feel that, since the chip is literally useless without those resistors, it would have made sense to emphasise that strongly in the datasheet (or at least mention it).

Also, it would have been useful to have the option of internal pull-ups on those lines, since the other I/O pins have them.

Hugo

 

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Editted

Dear Hugo,

We have already added the requirement of pull up resistors on I2C lines in CX3 datasheet. This can be found in Page 8 of CX3 datasheet. The snapshot of the same is attached below for your reference:

JayakrishnaT_76_0-1631859800698.png

Best Regards,
Jayakrishna
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